In a production line having a plurality of process modules that perform a predetermined process for a workpiece, popularly used is an industrial robot that transfers a workpiece among a plurality of process modules. For example, as shown in FIG. 6 and FIG. 7, an industrial robot 102 (i.e., a robot 102) is used in a production line 101 for producing semiconductors. The production line 101 includes an Equipment Front End Module (EFEM), being not illustrated in the drawings; and for example, four process modules 103, 104, 105, and 106. The process module 103 and the process module 104 are so placed as to be stacked in a vertical direction, and meanwhile the process module 105 and the process module 106 are so placed as to be stacked in a vertical direction. Moreover, the process modules 103 & 104 and the process modules 105 & 106 are so placed as to have a predetermined space between their two groups, in a direction X of horizontal directions in FIG. 6 and FIG. 7. Between the process modules 103 & 104 and the EFEM, provided is a buffer 108 for temporarily storing a semiconductor wafer W (a wafer W), as a workpiece, before supplying the wafer to the process modules 103 through 106. Incidentally, a wafer W stored in the EFEM is supplied to the buffer 108 by a robot being not illustrated in the drawings.
The robot 102 is equipped with an end effector 111 for grasping a wafer W. Concretely to describe, the robot 102 is equipped with two end effectors 111; one is for receiving a wafer W from the buffer 108, and the other is for placing a wafer W into the buffer 108. Furthermore, the robot 102 includes: an arm 112 to which the end effector 111 is connected so as to be rotatable; an arm driving mechanism for elongating/contracting the arm 112 to move the end effector 111 horizontally; a rotation mechanism for rotating the arm 112 around a root-end side portion of the arm 112 while using a vertical direction as a shaft direction; a lifting mechanism 113 for lifting up and down the end effector 111; and a transfer mechanism 114 for transferring the end effector 111 in the direction X. The robot 102 transfers the wafer W between the buffer 108 and the process modules 103 through 106.
In the production line 101, though sometimes the wafer W after being processed at one of the process modules 103 through 106 is subsequently supplied to another one of the process modules 103 through 106 for completing a predetermined process, the wafer W is usually returned to the buffer 108. Then, at each of the process modules 103 through 106, a predetermined processing operation is conducted on the wafer W. At first, in the production line 101, the robot 102 receives the wafer W, which has been supplied from the EFEM and stored in the buffer 108, from the buffer 108; and transfers the wafer W, for example, to the process modules 103. Then, the robot 1 takes out the processed wafer W from the process modules 103, and transfers the processed wafer W again to the buffer 108. Moreover, the robot 102 receives the wafer W from the buffer 108, and transfers the wafer W, for example, to the process modules 105. By way of repeating these operations, the production line 101 executes a predetermined process for the wafer W. Namely, in the production line 101, the predetermined process is executed for the wafer W with the robot 102 moving back and forth several times between the process modules 103 through 106, where the wafer W is processed, and the buffer 108.
Under conditions where a processed wafer W exists in the process modules 103 through 106; for example, at the time when a wafer W is transferred to the process module 103, the robot 102 at the process module 103 takes out the processed wafer W, which has been processed in the process module 103, from the process module 103 by using one of the two end effectors 111. At the same time, the robot 102 places a wafer W, which has been taken out from the buffer 108 and being grasped by the other of the two end effectors 111, into the process module 103. Subsequently, the robot 102 transfers the processed wafer W, which has been taken out from the process module 103 and being grasped by the said one of the two end effectors 111, to the buffer 108. Moreover, at the buffer 108, the robot 102 takes out a wafer W, to be processed in the process module 105 for example, from the buffer 108 by using the said other of the two end effectors 111. At the same time, the robot 102 places the wafer W, which has been taken out from the process module 103 and being grasped by the said one of the two end effectors 111, into the buffer 108.
For materialization of the production line 101 being efficient, it is important to appropriately balance a performance of processing wafers W by the process modules 103 through 106, a performance of transferring the wafers W by the robot 102, and a layout of the process modules 103 through 106, in the production line 101. Particularly in the case of the production line 101 in which the process modules 103 & 104 and the process modules 105 & 106 are so placed as to have a predetermined space between their two groups, in the direction X, as shown in FIG. 6 and FIG. 7; for materialization of the production line 101 being efficient, it is important to improve efficiency of transferring the wafers W. In other words, in the production line 101, for materialization of the production line 101 being efficient, it is important to increase a transfer speed of the robot 102 in the direction X.
In the meantime, unfortunately weight of a robot to be used generally in a production line for production of semiconductors and the like ranges from 50 to 100 kilograms, in accordance with a function in relation to the robot. Therefore, when it is intended to safely operate the robot 102 in the production line 101 for example, it is difficult to increase the transfer speed of the robot 102 in the direction X in such a way as to be faster than a conventional speed. Accordingly, it is difficult to improve a production efficiency of the production line 101, in such a way as to make it better than a conventional efficiency.
Thus, at least an embodiment of the present invention provides a workpiece transfer system in which a production efficiency of a production line to be used can be enhanced, and to provide a workpiece transfer system in which a production efficiency of a production line can be improved particularly when being used in a production line where a workpiece such as a semiconductor and the like is transferred for a relatively long distance.
To bring a solution for the subject described above, a workpiece transfer system according to at least an embodiment of the present invention includes; a robot placed in front of a process module for conducting a predetermined processing operation on a workpiece, the robot bringing the workpiece into the process module and taking the workpiece out of the process module; a workpiece storage unit for storing the workpiece to be brought into the process module and the workpiece taken out of the process module; and a transfer mechanism for transferring the workpiece storage unit in a direction almost perpendicular to a direction of bringing in and taking out the workpiece for the process module.
The workpiece transfer system according to at least an embodiment of the present invention includes the workpiece storage unit for storing the workpiece, and the transfer mechanism for transferring the workpiece storage unit in the direction almost perpendicular to the direction of bringing in and taking out the workpiece for the process module. Therefore, simply needed is to transfer the workpiece storage unit instead of the robot, in the direction almost perpendicular to the direction of bringing in and taking out the workpiece for the process module, wherein the workpiece storage unit being able to have a reduced lighter weight, compared to the robot. Accordingly, the workpiece storage unit can safely be transferred even though a transfer speed of the workpiece storage unit is set to be higher than a transfer speed of the robot. In other words, efficiency of transferring the workpiece can be improved by way of increasing the transfer speed of the wafer storage unit. As a result, production efficiency of the production line, in which the workpiece transfer system is used, can be improved. Furthermore, the transfer speed of the wafer storage unit can be increased, and therefore if the workpiece transfer system according to at least an embodiment of the present invention is used in a production line in which a workpiece is transferred for a comparatively long distance, the production efficiency of the production line can be further improved.
In at least an embodiment of the present invention, it is preferable that the workpiece transfer system includes a plurality of robots laid out in the transfer direction of the workpiece storage unit and the workpiece storage unit is able to store a plurality of workpieces. According to this configuration, for example, at an installation spot of the buffer 108 explained with reference to FIG. 6 and FIG. 7, a plurality of wafers can be stored in the workpiece storage unit. Therefore, in the case where this workpiece transfer system is used in a production line in which a plurality of process modules are placed in the transfer direction of the workpiece storage unit; even though, after one of the plurality of robots takes out a workpiece, the workpiece storage unit moves directly to a installation spot of another of the robots without returning to the installation spot of the buffer, the latter robot can take out a workpiece stored in the workpiece storage unit. Accordingly, the production efficiency of the production line, in which the workpiece transfer system is used, can effectively be improved.
In at least an embodiment of the present invention, it is preferable that the workpiece storage unit is placed between the process module and the robot, in the direction of bringing in and taking out the workpiece for the process module. According to this configuration, it is simply needed for an end effector of the robot to move from a specified standby position toward the workpiece storage unit, and further move in the same direction as it has done, even after receiving a workpiece at the workpiece storage unit in order to bring the workpiece into the process module. Moreover, the end effector that has moved from the process module toward the workpiece storage unit and stored the workpiece in the workpiece storage unit simply needs to move in the same direction as it has done, to the specified standby position. Therefore, control of the robot can be simplified.
In at least an embodiment of the present invention, it is preferable that the workpiece transfer system includes: a plurality of workpiece storage units placed so as to be stacked in a vertical direction, a plurality of transfer mechanisms for transferring each of the plurality of workpiece storage units, and a plurality of robots, the number of robots being equal to or greater than the number of the plurality of workpiece storage units; wherein each of the robots includes; an end effector on which the workpiece is mounted, and a lifting mechanism for lifting up and down the end effector; the plurality of robots are placed in a transfer direction of the workpiece storage units; the plurality of workpiece storage units are placed below the plurality of robots; and a lower limit position of each moving range of the end effector provided to each of the plurality of robots is lowered in a stepwise manner in the transfer direction of the workpiece storage units, and the lower limit position is set according to an elevation of each of the plurality of workpiece storage units. According to this configuration, it is possible to associate one of the plurality of workpiece storage units with one of the plurality of robots one-on-one. As a result, the workpiece transfer system can be controlled easily. Furthermore, according to this configuration, a lower limit position of each moving range of the end effector provided to each of the plurality of robots is lowered in a stepwise manner in the transfer direction of the workpiece storage units, and the lower limit position is set according to an elevation of each of the plurality of workpiece storage units; and therefore, it becomes possible to prevent an interference of a robot associated with a certain workpiece storage unit and any workpiece storage unit other than the workpiece storage unit associated with the robot, by way of adjusting moving ranges of the plurality of workpiece storage units. Then, it becomes possible to carry out operations of the plurality of robots and transfers of the plurality of workpiece storage units at the same time freely. As a result, the production efficiency of the production line, in which the workpiece transfer system is used, can effectively be improved.
In at least an embodiment of the present invention, it is preferable that the workpiece storage units, being placed below the robots, move through an area away from a working space of the robots. According to this configuration, it becomes possible to prevent an interference of the robots during operations and the workpiece storage units in motion. Then, it becomes possible to carry out operations of the robots and transfers of the workpiece storage units at the same time freely. As a result, the production efficiency of the production line, in which the workpiece transfer system is used, can effectively be improved. Furthermore, according to this configuration, process modules can be placed at both sides of the robots in a direction of bringing in and taking out a workpiece.
As described above, at least an embodiment of the present invention makes it possible to improve a production efficiency of a production line in which a workpiece transfer system is used.